Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Diffuse Calcium-Containing Crystal Deposits in Human Osteoarthritic Articular Cartilage: Not Limited to the Medial Compartment.

Nguyen4,  Christelle, Ea4,  Hang-Korng, Hannouche2,  Didier, Daudon3,  Michel, Bazin1,  Dominique, Liote4,  Frédéric

Laboratoire de Physique des Solides; Paris Sud University; Orsay; France
Orthopaedic Surgery Department; Lariboisière Hospital; Paris Diderot University; Assistance Publique-Hôpitaux de Paris (AP-HP), Paris
Service de Biochimie A; Necker Hospital; Paris Sud University; AP-HP; Paris
UMR-S 606, INSERM & Paris Diderot University; PRES Sorbonne Paris-Cite; Lariboisiere Hospital; Paris; France

Purpose:

Calcium-containing crystals (CC), including basic calcium phosphate crystals (BCP) and calcium pyrophosphate crystals (CPP) are associated with destructive forms of osteoarthritis (OA). Recent reports showed that mineralization of articular cartilage of the medial compartment is an indissociable process of end-stage OA. However, accurate characterisation of CC by conventional techniques remains challenging.

Objectives:

To assess biochemical composition and spatial distribution of mineral phases in human OA cartilage, and to determine their morphological aspects.

Methods:

Fourteen patients (12 women and 2 men), who underwent total knee joint replacement for primary OA, were prospectively included. A 24-year-old woman who underwent total knee joint replacement for chondrosarcoma served as control. Specimen included femoral condyle and tibial plateau cartilages, from both medial and lateral compartments. Clinical data and preoperative knee X-rays were obtained. For each femoro-tibial compartment, 4 samples (2 from femoral condyles and 2 from tibial plateau) were collected, consisting in 1-mm-thick slices. Slices were cut tangentially to the articular surface, within the superficial and deep layers of the articular cartilage, respectively. Biochemical composition was assessed using Fourier-transform infra-red (FTIR), and morphological aspects were determined using scanning electron microscopy (SEM). All results are expressed as mean (SD).

Results:

Age and body mass index at the time of intervention were 74.4 (8.3) years, and 28.8 (6.2) kg/m2, respectively. Preoperative X-rays found uni-, bi- or tricompartmental knee OA in 2, 8 and 4 cases, respectively. In all cases, the compartment mainly affected was medial femoro-tibial, and Kellgren and Lawrence score was 3.8 (0.4). Joint calcifications were detected in only 2 cases on preoperative X-rays, but in 11 cases under macroscopic examination. FTIR analysis showed CC in all 14 specimens. CC were absent from the control sample. The overall mineral content represented 9.1 (12.6)%. CC were identified as BCP only in 6 patients, and as both BCP and CCP in 8. Remarkably, CC were widespread in all knee joint compartments and involved at least 3 areas out of 8 in all specimens. In addition, CC distribution was similar between superficial and deep layers, and between medial and femoral compartments (11.1 [14.7]% vs 7.3 [10.2]%, and 8.1 [11.2]% vs 9.5 [13.1]%, p=NS, respectively). Finally, SEM identified 2 different morphological aspects: 1/spherical structures, typical of biological apatite, resulting from an agglomeration of nm-scale cristallites surrounded by proteins, and localized in structures suggestive of chondrons, in the BCP-containing samples; 2/ acicular or cubic structures of different sizes, in the CPP-containing samples.

Conclusions:

CC are constantly found in human OA articular cartilage at the time of knee joint replacement. Cartilage calcifications occur in all knee joint compartments, even in less weight-bearing ones, suggesting that cartilage mineralization process may reflect a generalized chondrocyte disease. In addition, their morphological aspects are specific to the crystal type.

To cite this abstract, please use the following information:
Nguyen, Christelle, Ea, Hang-Korng, Hannouche, Didier, Daudon, Michel, Bazin, Dominique, Liote, Frédéric; Diffuse Calcium-Containing Crystal Deposits in Human Osteoarthritic Articular Cartilage: Not Limited to the Medial Compartment. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :875
DOI: 10.1002/art.28643

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